** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** INVASIVE SPECIES, DEFINED AS SPECIES THAT ARE MOVED OUT OF THEIR NATIVE RANGE BY HUMANS AND CAUSE ENVIRONMENTAL AND ECONOMIC DAMAGE, ARE A GROWING PROBLEM AS GLOBALIZATION INCREASES. THE FIELD OF INVASION BIOLOGY IS RELATIVELY NEW, AND AS A RESULT MANY HYPOTHESES ON THE MOVEMENT, SUCCESS, AND IMPACT OF INVASIVE SPECIES REQUIRE ADDITIONAL EMPIRICAL EVIDENCE. A KEY HYPOTHESIS IN INVASION BIOLOGY, BUT ONE WITH LIMITED EMPIRICAL EVIDENCE, IS THE INVASIONAL MELTDOWN HYPOTHESIS, WHICH PROPOSES THAT AN ECOSYSTEM THAT HAS BEEN INVADED BY ONE SPECIES IS MORE VULNERABLE TO FURTHER INVASIONS. THIS VULNERABILITY RESULTS FROM FACILITATION OR MUTUALISM BETWEEN TWO NON-NATIVE SPECIES. HOWEVER, INVASIVE SPECIES MAY ALSO NEGATIVELY IMPACT EACH OTHER, FOR EXAMPLE BY COMPETING FOR THE SAME RESOURCES. ONE QUESTION THAT HAS NOT BEEN THOROUGHLY INVESTIGATED IS WHAT HAPPENS TO AN INVASIVE SPECIES WHEN IT FACILITATES THE INVASION OF A SECOND SPECIES THAT OCCUPIES A SIMILAR ECOLOGICAL NICHE? WOULD FACILITATION OR COMPETITION BE THE PREDOMINANT DRIVER OF POPULATION DYNAMICS OF BOTH SPECIES? THE EXACT NATURE OF SUCH AS RELATIONSHIP WOULD HAVE A SIGNIFICANT IMPACT ON EACH SPECIES' POPULATION DYNAMICS AND HOW THEY EXPLOIT RESOURCES, SO IT IS CRITICAL TO UNDERSTAND THESE RELATIONSHIPS TO PREDICT AND MANAGE THE IMPACTS OF SECONDARY FACILITATED INVASION. IN THIS STUDY WE WILL EXAMINE THE RELATIONSHIP BETWEEN TWO IMPORTANT ECONOMIC PESTS, SPOTTED WING DROSOPHILA (SWD) AND AFRICAN FIG FLY (AFF). SWD IS A PRIMARY PEST OF SOFT FRUITS. IT HAS A SERRATED OVIPOSITOR WHICH ALLOWS IT TO LAY ITS EGGS ON RIPENING FRUIT ON THE VINE CAUSING LARGE AMOUNTS OF ECONOMIC DAMAGE. AFF DOES NOT HAVE THE SAME SERRATED OVIPOSITOR AND LACKS THE ABILITY TO PUNCTURE THE RIPENED FRUIT ITSELF. HOWEVER, AFF CAN UTILIZE THE DAMAGE CAUSED BY SWD AND LAY ITS EGGS IN THE SAME FRUIT AND BECOME A SECONDARY PEST. IN THIS WAY, SWD FACILITATES THE INVASION OF AFF. HOWEVER, BECAUSE OF THIS RELATIONSHIP, THE TWO SPECIES ARE ALSO COMPETING FOR THE SAME LIMITED RESOURCE, WHICH COULD NEGATIVELY IMPACT BOTH OF THEIR POPULATIONS. BY EXPLORING THIS RELATIONSHIP, WE WILL EXPAND OUR KNOWLEDGE OF INVASIVE SPECIES BIOLOGY, IN PARTICULAR INVASIONAL MELTDOWN THEORY, AND INCREASE KNOWLEDGE ON THE BIOLOGY AND POPULATION DYNAMICS OF TWO IMPORTANT ECONOMIC PESTS. OUR SPECIFIC OBJECTIVES OF THIS PROJECT ARE 1. DETERMINE THE EXTENT THAT AFRICAN FIG FLY RELIES ON SPOTTED WING DROSOPHILA TO INFEST SMALL BERRY CROPS. 2. IDENTIFY ENVIRONMENTAL FACTORS THAT AFFECT COMPETITION BETWEEN SPOTTED WING DROSOPHILA AND AFRICAN FIG FLY. 3. TO DETERMINE HOW THE PRESENCE OF BOTH SPOTTED WING DROSOPHILA AND AFRICAN FIG FLY IN A CROPPING SYSTEM AFFECTS THE QUALITY AND MARKETABILITY OF CROPS.TO ACCOMPLISH OUR OBJECTIVES WELL WILL RUN A SERIES OF LAB-BASED EXPERIMENTS, A GREENHOUSE STUDY, AND FIELD MONITORING. TO DETERMINE IF AFF RELIES OF SWD TO INFECT FRUIT WE WILL CONDUCT A LAB BASED NO-CHOICE TEST WHERE WE TEST THE ABILITY OF AFF TO LAY EGGS IN D,IFFERENT TYPES OF FRUIT WITH DIFFERENT RIPENESS, AND DAMAGE TYPES. THIS STUDY WILL PROVIDE INFORMATION ON WHETHER AFF COULD BE A PRIMARY PEST IN DIFFERENT FRUIT CROPS. WE WILL ALSO CONDUCT A CHOICE EXPERIMENT WHERE AFF CAN CHOOSE BETWEEN NON-DAMAGED, MECHANICALLY DAMAGED, AND FRUITS DAMAGED BY SWD. THIS EXPERIMENT WILL HELP US UNDERSTAND IF SWD DAMAGE MAKES FRUIT MORE ATTRACTIVE TO AFF. TO EXPLORE THE COMPETITION BETWEEN SWD AND AFF, WE WILL CONDUCT TWO SETS OF EXPERIMENTS, ONE WHERE THE SPECIES COMPETE IN DIFFERENT FRUIT CROPS, AND A SECOND WHERE THEY COMPETE AT DIFFERENT TEMPERATURES. THESE RESULTS WILL GIVE INSIGHT ON HOW BOTH NUTRITION AND TEMPERATURE COULD AFFECT COMPETING POPULATIONS OF AFF AND SWD IN THE FIELD. FINALLY, WE WILL DETERMINE HOW BOTH HAVING BOTH SPECIES PRESENT AFFECTS CROPS BY CONDUCTING A CAGE EXPERIMENT, WHERE PLANTS GROWN IN INDUVIAL CAGES WILL HAVE FLIES INTRODUCED INTO THE CAGE. WE WILL THEN COMPARE THE YIELD AND QUALITY OF THE FRUIT PRODUCED IN CAGES WITH BOTH SPECIES COMPARED TO CAGES WITH ONE SPECIES, OR NO FLIES PRESENT. THIS CONTROLLED EXPERIMENT WILL BE SUPPLEMENTED BY FIELD MONITORING WHERE WE WILL TRAP AND COLLECT FLIES FROM FRUIT TO CONFIRM NATURAL POPULATION SIZES. THIS INFORMATION WILL PROVIDE INSIGHT ON HOW THE PRESENCE OF BOTH FLIES WILL INFLUENCES CROP PRODUCTION. RESULTS FROM ALL OUR OBJECTIVES WILL BE PUBLISHED IN SCIENTIFIC PAPERS, AS WELL AS SPOKEN OUT AT SCIENTIFIC CONFERENCES. WE WILL ALSO CREATE EXTENSION MATERIAL WITH OUR RESULTS IN THE FORM OF FACT SHEETS, GROWER TALKS, AND EXTENSION EVENTS WHICH WILL ALLOW ANY KNOWLEDGE GAINED TO GET PASSED DIRECTLY TO GROWERS AND EXTENSION AGENTS.IN COMPLETING OUR PROJECT, THERE WILL BE IMPROVED FUNDAMENTAL KNOWLEDGE ABOUT INTERACTIONS BETWEEN INVASIVE SPECIES. THIS INFORMATION WILL ALLOW US TO BETTER UNDERSTAND AND PREDICT WHAT MAY HAPPEN BETWEEN TWO SPECIES THAT ARE COMPETING FOR AND ALTERING THE SAME RESOURCE. THERE WILL ALSO BE GREATER PRACTICAL KNOWLEDGE ON TWO PEST SPECIES AND HOW THEY INTERACT WITH EACH OTHER. THE KNOWLEDGE FROM THIS RESEARCH COULD CHANGE HOW RESEARCHERS, GROWERS, AND EXTENSION AGENTS THINK ABOUT THESE TWO FLY SPECIES, POTENTIALLY LEADING TO NEW RECOMMENDATIONS FOR HOW WE MONITOR AND BUILD MANAGEMENT PRACTICES. TOGETHER, THIS WORK WILL INCREASE INFORMATION FOR GROWERS AND SCIENTISTS ON AN UNDERSTUDIED PEST (AFF) AND ITS IMPACT ON AN ECONOMICALLY IMPORTANT PEST (SWD).